Generally, a motor includes a stator applied with a power, and a rotor rotating in interaction with the stator. The stator in turn includes a stator core and a stator coil wound on the stator core. The rotor includes a plurality of magnets arranged inside the stator and a rotation shaft to which the magnets are fixed.
FIG. 1 is a schematic views of a stator core according to prior art.
The stator core (1) according to the prior art includes a plurality of teeth (3) radially arranged and wound by a coil (5) and a ring-shaped core wheel (2) integrally connected to a periphery of the teeth (3), where the core wheel (2) is integrally formed with the periphery of the teeth (3) and magnets (6) are integrally arranged at an inner circumference of the teeth. At this time, a jig is inserted to a gap between the teeth (3) to wind the coil (5) on each tooth (3).
However, it is problematic to wind the coil (5) on each tooth (3) through a narrow gap, which takes a lot of time for winding and needs an expensive coil winding machine. In order to solve the problems, a stator core (10) is proposed in which an inner core (11) having a plurality of radially connected teeth (13), and an outer core (12) secured to an external end of the teeth (13) is separated, as shown in FIG. 2.
The stator core (10) is configured in such a manner that a coil (14) is wound on each tooth (13), and a distal end of each tooth (13) is fixed with the outer core (12). However, the stator core (10) is also problematic in that an expensive mold has to be employed to ensure a dimensional accuracy at an area where the inner core (11) and the outer core (12) are mutually coupled, a separate exclusive jig must be used to couple the inner core to the outer core, and assembly work becomes complicated because the inner core must be coupled to the outer core that is thermally expanded, when the inner core and the outer core are coupled.